Connection apparatus for optical coherence tomography catheters

ABSTRACT

An optical catheter connection system is described which has two mating assemblies: a motor unit and an optical catheter connector. The optical catheter connector mates to the motor unit for coupling optical signal into and out of a catheter optical fiber and providing drive torque to the catheter optical fiber. The motor unit includes a rotary shaft powered by a motor for providing drive torque to the catheter optical fiber to rotate the fiber. The motor unit further includes a split sleeve for aligning a motor optical fiber with the catheter optical fiber for coupling optical signals between the two fibers. In one embodiment, a shield is provided around the outer surface of the optical catheter connector to help maintain a sterile field by forming a barrier between a clinician&#39;s sterile hand, which holds the optical catheter connector, and the non-sterile motor unit.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to medical device connectors, andmore particularly to optical catheter connectors.

[0003] 2. Background

[0004] Optical Coherence Tomography (OCT) is an optical imagingtechnique, which achieves non-invasive, cross-sectional imaging of apatient's body. OCT is analogous to ultrasound imaging, only measuringthe intensity of back-scattered infrared light rather than ultrasound.To image the blood vessel of a patient using OCT, an optical catheter isinserted into the blood vessel. An optical signal is transmitted throughan optical fiber in the optical catheter and emitted at the distal endof the catheter into the blood vessel. The optical signal is typicallyproduced by a laser, e.g., laser diode. The optical signal reflectedback to the catheter from the blood vessel and surrounding tissue istransmitted through the optical fiber to an interferometer, whichoptically processes the reflected optical signal to obtain a depth imageof the blood vessel.

[0005] An OCT connection system couples optical signals produced by alight source, e.g., laser, into the catheter optical fiber to be emittedinside the body. The OCT connection system then couples the reflectedoptical signal out of the catheter optical fiber to an interferometer toobtain a image of the inside of the body. In addition, the OCTconnection system may include a motor unit for providing drive torque tothe catheter optical fiber to rotate the catheter optical fiber duringimaging. This enables a radial cross-sectional image of the inside ofthe body to be obtained.

[0006] There are many challenges in designing a high performance,ergonomic catheter connector. The requirements of a good connectordesign include sterile field maintenance, reliable high performancecomponents, ease of assembly and an intuitive connection procedure. Agood design should provide a connection system that meets all theserequirements while keeping the cost of the disposable portion of theconnector low. The design should provide a positive lock between acatheter connector and a motor unit to prevent accidental disconnectionof the catheter or degradation of performance if the catheter is used topull the motor unit. It should also provide a clear indication thatproper engagement between the catheter connector and the motor unit isachieved.

SUMMARY OF THE INVENTION

[0007] The invention provides an OCT connection system comprising twomating assemblies, a motor unit and an OCT catheter connector. The OCTcatheter connector mates to the motor unit for coupling optical signalsinto and out of a catheter optical fiber and for providing drive torqueto the catheter optical fiber.

[0008] A motor unit, built in accordance with a first example embodimentof the invention, includes a motor nose with an opening at its distalend, a rotary shaft housed in the motor nose, a connector assemblyhoused in and attached to the rotary shaft, and a fiber-to-fiber adaptermounted to the rotary shaft. The rotary shaft, the connector assemblyand the fiber-to-fiber adapter all rotate together within the motor noseand form the mechanical rotating portion of the motor unit. The motorunit further includes a motor optical fiber that runs along therotational axis of the connector assembly. One end of the motor fiber issupported by a motor fiber ferrule, which is inserted into one end of asplit sleeve in the fiber-to-fiber adapter. As used here, the term“ferrule” refers to a hollow structure of any shape or configuration.For example, while preferably the motor fiber ferrule is cylindrical, itcan be hexagonal. As another example, a motor fiber ferrule may be ahollow band surrounding the motor optical fiber and protects or givessupport to the motor optical fiber.

[0009] The OCT catheter connector includes a catheter ferrule with anopening at its proximal end, a connector bushing rotatably housed withinthe catheter ferrule, and an optical fiber catheter connector attachedto the connector bushing. The OCT connector also includes a catheteroptical fiber that runs along the rotational axis of the catheter fiberconnector. One end of the catheter optical fiber is supported by acatheter fiber within the catheter fiber connector.

[0010] The OCT catheter connector is mated to the motor unit byinserting the fiber connector into the fiber-to-fiber adapter throughthe opening in the motor nose. As the fiber connector is inserted intothe fiber-to-fiber connector, the catheter fiber ferrule supporting thecatheter optical fiber is inserted into the other end of the splitsleeve in the fiber-to-fiber adapter. The split sleeve aligns thecatheter optical fiber with the motor optical fiber to couple opticalsignals between the two fibers. The fiber-to-fiber adapter includesretaining clips for locking the catheter fiber connector in place onceproper engagement is achieved. The opening of the motor nose is equippedwith tab slots adapted to receive snap lock tabs on the OCT catheterconnector. Once the OCT catheter connector is properly mated to themotor unit, the rotary shaft provides drive torque to the catheter fiberconnector and the catheter optical fiber via the fiber-to-fiber adapter.

[0011] The snap locks of the OCT catheter connector may include grippersfor pushing the catheter fiber connector into proper engagement with thefiber-to-fiber adapter. To do this, the grippers engage slots on theconnector bushing through slot openings in the catheter ferrule. Thisengagement holds the connector bushing stationary with respect to thecatheter ferrule so that the connector bushing pushes the catheter fiberconnector into the fiber-to-fiber adapter as the OCT catheter connectoris inserted into the motor unit. When proper engagement is achieved, thegrippers retract from the slots on the connector bushing, allowing thecatheter fiber connector to freely rotate within the catheter ferrule ofthe OCT catheter connector.

[0012] The OCT catheter connector may include an ‘O’-ring fitted arounda grooved portion of the catheter fiber connector to provide a dynamicseal to block fluid from contaminating the catheter fiber connector. TheOCT catheter also may include a free floating ‘O’-ring housing tocompensate for any eccentric rotation of the catheter fiber connector.

[0013] An OCT catheter connector, built in accordance with a secondexample embodiment, comprises a flexible catheter ferrule and a rigidretainer within the catheter ferrule. The retainer provides rigidity tothe catheter ferrule. The OCT catheter connector also includes aconnector bushing and a catheter fiber connector attached to theconnector bushing. The connector bushing may include ribs that arepositioned at cutouts in the retainer.

[0014] The OCT catheter connector according to this second exampleembodiment is mated to the motor unit by slightly squeezing a grip areaof the catheter ferrule corresponding to the cutouts of the retainer.The squeezing deforms the catheter ferrule within the grip area, causingthe catheter ferrule to contact the ribs of the connector bushingthrough the cutouts in the retainer. This contact holds the connectorbushing stationary with respect to the OCT catheter connector so thatthe connector bushing pushes the catheter fiber connector intoengagement with the motor unit as the OCT catheter connector is insertedinto the motor unit. Once the OCT catheter connector is properly matedto the motor unit, the catheter ferrule elastically regains its originalshape, allowing the connector bushing and the catheter fiber to freelyrotate within the catheter ferrule.

[0015] The OCT connector according to this second example embodimentalso preferably includes a shield running around the outer cylindricalsurface of the catheter ferrule to help maintain a sterile field byforming a barrier between a clinician's sterile hand, which holds theOCT connector, and the non-sterile motor unit. The OCT connector alsomay have short ribs on the outer cylindrical surface of the catheterferrule to snap into mating grooves in the motor unit to preventunwanted disconnection of the OCT connector from the motor unit.

[0016] A motor unit, built in accordance with a third exampleembodiment, includes three spring loaded ball plungers radially locatedpreferably 120 degrees apart on the motor nose. Each one of the threeball plungers has a spherical ball positioned to engage a correspondingconcave depression in the OCT catheter connector to secure the OCTconnector to the motor unit via frictional resistance. The motor nosefurther may include a bendable wave or Belleville washer surrounding thefiber-to fiber adapter of the motor unit.

[0017] To insert the OCT connector into the motor unit, the catheterferrule of the OCT connector is pushed into the motor unit. As thecatheter ferule is pushed into the motor unit, the distal end of theconnector bushing contacts a portion of the inner wall of the catheterferrule. This contact causes the portion of the inner wall of thecatheter ferrule to push against the connector bushing, which in turncauses the connector bushing to push the catheter fiber connector intoengagement with the fiber-to-fiber adapter of the motor unit. Alsoduring insertion of the OCT connector into the motor unit, the proximalend of the catheter ferrule pushes the washer surrounding thefiber-to-fiber adapter inwardly. When the catheter ferrule is releasedafter proper engagement has been achieved, the washer pushes thecatheter ferrule distally with respect to the connector bushing. Thiscauses the portion of the inner wall of the catheter ferrule to moveaway from the connector bushing, allowing the connector bushing torotate freely within the catheter ferrule without friction or sideloading.

[0018] The catheter ferrule according to this third example embodimentmay be constructed of a rigid, injection moldable material as one pieceor two pieces comprising a shield that is bonded to the cylindrical bodyof the ferrule that acts as a sterile barrier to prevent thecontamination of the clinician's sterile hand during attachment of thecatheter to the non-sterile motor unit.

[0019] The OCT connector according to this third example embodiment mayinclude drain holes to allow fluid leakage to drain through the wall ofthe ferrule to reduce the likelihood of contamination of the motor unitand the fiber optic connector if the ‘O’-ring seal should leak duringhigh-pressure infusion. In addition, the ‘O’-ring according to thisembodiment seals around a gland instead of a grooved portion of thecatheter connector. The gland is a stainless steel tube with a smoothouter surface finish that is bonded into the catheter fiber connectorusing epoxy to form a high pressure seal.

[0020] The details presented in this Section are provided asillustrative examples only, are not necessarily required by theinvention and should not be used to limit the scope of the invention.Other systems, methods, features and advantages of the invention will beor will become apparent to one with skill in the art upon examination ofthe following figures and detailed description. It is intended that allsuch additional systems, methods, features and advantages be includedwithin this description, be within the scope of the invention, and beprotected by the accompanying claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The components in the figures are not necessarily to scale,emphasis instead being placed upon illustrating the principles of theinvention. Moreover, in the figures, like reference numerals designatecorresponding parts throughout the different views. FIG. 1 shows anaxial cross-sectional view of a first embodiment of an improved OCTcatheter connection system.

[0022]FIG. 2 shows a blown-up axial cross-sectional view of the OCTcatheter connector.

[0023]FIG. 3 shows a perspective view of the OCT catheter connector.

[0024]FIG. 4 shows a radial cross-sectional view of the OCT catheterconnector taken along line 4-4.

[0025]FIG. 5 shows an end view of the OCT catheter connector and themotor unit looking proximally.

[0026]FIG. 6 shows a radial cross-sectional view of the OCT catheterconnector taken along line 6-6.

[0027]FIG. 7 shows an axial cross-sectional view of the motor unit ofthe OCT catheter connection system.

[0028]FIG. 8 shows an axial cross-sectional view of a second embodimentof an improved OCT catheter connector.

[0029]FIG. 9 shows an axial cross-sectional view of a third embodimentof an improved OCT connection system.

[0030]FIG. 10 shows a blown-up cross-sectional view of the OCTconnection system in FIG. 9.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0031]FIG. 1 illustrates an axial cross-sectional view of a firstexample embodiment of an OCT catheter connection system. The OCTcatheter connection system comprises two mating assemblies, an OCTcatheter connector 1 and a motor and optical rotary joint unit 3,hereinafter, the “motor unit” for simplicity. The distal portion of themotor unit 3 is shown in FIG. 1.

[0032] The motor unit 3 includes a motor nose 14 with an opening 13 atits distal end, a rotary shaft 2 housed in the motor nose 14, aconnector assembly 6 housed in and attached to the rotary shaft 2, and afiber-to-fiber adapter 10 mounted to the rotary shaft 2 with screws. Therotary shaft 2, the connector assembly 6 and the fiber-to-fiber adapter10 all rotate together within the motor nose 14 and form the mechanicalrotating portion of the motor unit 3. The motor unit 3 also includes amotor optical fiber 4 that runs along the rotational axis of theconnector assembly 6. The motor optical fiber 4 may be a single-mode ora multiple-mode optical fiber. The fiber-to-fiber adapter 10 includes asplit sleeve 12, which may be made of ceramic or metal. One end of themotor optical fiber 4 is supported by a motor fiber ferrule 8, which isinserted into one end of the split sleeve 12.

[0033]FIG. 2 shows a blown up cross-sectional view and FIG. 3 shows aperspective view of the OCT catheter connector 1. The OCT catheterconnector 1 includes a hollow catheter ferrule 52 with an opening 53 atits proximal end and a connector bushing 30 housed in the catheterferrule 52. The catheter ferrule 52 is preferably made of polycarbonateor injection-molded plastic. Space is provided between the connectorbushing 30 and the inner walls of the catheter ferrule 52 so that theconnector bushing 30 can freely rotate within the catheter ferrule 52. Aretainer 26 is provided along the opening 53 of the catheter ferrule 52to prevent the connector bushing 30 from falling out of the catheterferrule 52. The OCT catheter connector 1 further includes a fiberconnector 32 attached to the connector bushing 30, e.g., with epoxy, anda catheter optical fiber 60 that runs along the rotational axis of thecatheter fiber connector 32. One end of the catheter fiber 60 issupported by a catheter fiber ferrule 24 attached to the catheter fiberconnector 32. The catheter fiber ferrule 24 extends outwardly from theopening 53 of the catheter ferrule 52. The OCT catheter connector 1 alsopreferably includes snap lock tabs 36 attached to the outer surface ofthe catheter ferrule 52. Preferably, the snap lock tabs 36 are made of asemi-rigid material, such as plastic, so that they can be compressed,e.g., by a clinician's fingers. The snap lock tabs 36 may be made of thesame piece as the catheter ferrule 52 or may be made of separate piecesattached to the catheter ferrule 52, e.g., with epoxy.

[0034] Referring to FIG. 1, the OCT catheter connector 1 is mated to themotor unit 3 by inserting the catheter fiber connector 32 into thefiber-to-fiber adapter 10 through the opening 13 in the motor nose 14.As the fiber connector 32 is inserted into the fiber-to-fiber adapter10, the catheter fiber ferrule 24 is inserted into the other end of thesplit sleeve 12. The split sleeve 12 aligns the catheter optical fiber60 with the motor optical fiber 4 to couple optical signals between thetwo fibers 60 and 4. A guide 20 bonded to the fiber-to-fiber adapter 10,e.g., with epoxy, provides guidance for the catheter fiber connector 32into the fiber-to-fiber adapter 10 in case of slight misalignment duringinsertion. The fiber-to-fiber adapter 10 includes retaining clips 16 forlocking the catheter fiber connector 32 in place once proper engagementis achieved. The retaining clips 16 prevent the catheter fiber connector32 from being detached from the motor unit 3 by pulling the cathetershaft 56 (discussed later) of the OCT connector 1. The opening 13 of themotor nose 14 has tab slots 18 adapted to receive the snap lock tabs 36of the OCT catheter connector 1. The snap lock tabs 36 are locked in thetab slots 18 by protuberances 22 on the tab slots 18. The protuberances22 are best illustrated in FIG. 5, which shows a front view of the OCTconnector 1 mated to the motor unit 3. Each snap lock tab 36 includesflanges 37 adapted to engage the protuberances 22. The snap lock tabs 36are compressed as the OCT connector 1 is inserted into the motor unit 3,allowing the flanges 37 to clear the protuberances 22 on the tab slots18. Once the snap lock tabs 36 are inserted into the tab slots 18 andreleased, the flanges 37 engage the protuberances 22, thereby lockingthe snap lock tabs 36 in the tab slots 18. Preferably, an audible clickis produced when the snap lock tabs 36 snap into place in the tab slots18. Once the OCT catheter connector 1 is mated to the motor unit 3,rotation of the rotary shaft 2 by a motor (not shown) provides drivetorque to the catheter fiber connector 32 and the catheter fiber 60 viathe fiber-to-fiber adapter 10.

[0035] The catheter fiber connector 32 is detached from the motor unit 3by compressing finger tabs 38 on the snap lock tabs 36. This allows theflanges 37 on the snap lock taps 36 to clear the protuberances 22 on thetab slots 18 and the OCT connector 1 to be pulled out of the motor unit3.

[0036] The snap lock tabs 36 includes grippers 34 for providinginsertion force to the catheter fiber connector 32 to push the catheterfiber connector 32 into proper engagement with the fiber-to-fiberadapter 10. To do this, the snap lock tabs 36 are compressed so that thegrippers 34 engage slots 44 on the connector bushing 30 through slotopenings 72 in the catheter ferrule 52. The grippers 34 hold theconnector bushing 30 stationary with respect to the OCT connector 1 sothat the bushing 30 pushes the catheter fiber connector 32 into thefiber-to-fiber adapter 10 as the OCT connector 1 is inserted into themotor unit 3. The grippers 34 retract when the snap lock tabs 36 clickinto place in the tab slots 18 when, and thereby indicating, properengagement has been achieved. This allows the connector bushing 30 andthe catheter connector 32 to freely rotate within the catheter ferrule52 without any support other than that provided by the fiber-to-fiberadapter 10 of the motor unit 3. This is important because any lateralforces acting on the catheter fiber connector 32 during rotation cancause flexing of the ‘optical connection’, which can result in unwantedlosses or variation in optical power coupled into the catheter fiber 60.

[0037] A seal 46, preferably, an ‘O’-ring, is optionally used to providea dynamic seal to block fluid from contaminating the OCT catheterconnector 1. The ‘O’-ring 46 is fitted around a grooved portion of thecatheter fiber connector 32. The ‘O’-ring 46 also provides frictionalresistance to rotation of the catheter fiber connector 32 so that itretains its rotational position relative to the catheter ferrule 52 whenthe OCT catheter connector 1 is detached from the motor unit 3. Arelatively large clearance is provided between the connector bushing 30and the inner wall of the catheter ferrule 52 to allow the bushing 30 tofreely rotate, even when the bushing 30 rotates eccentrically.

[0038] The OCT catheter connector 1 further includes an ‘O’-ring housing50 within the catheter ferrule 52. The ‘O’-ring housing 50 has anannular slot that fits around the ‘O’-ring 46. The catheter fiber 60runs through the axis of the ‘O’-ring housing 50. The ‘O’-ring housing50 is free floating within the catheter ferrule 52 without any rigidmounts in order to compensate for any eccentric rotation of the catheterfiber connection 32. A relatively large clearance is provided betweenthe ‘O’-ring housing 50 and the catheter ferrule 52 to allow the‘O’-ring housing 50 to follow an orbit as the catheter fiber connector32 rotates in an eccentric path. In this example embodiment, the‘O’-ring housing 50 has a square outer profile and the portion 53 of thecatheter ferrule 52 enclosing the ‘O’-ring housing 50 has acorresponding a square inner profile. This is best illustrated by FIG.4, which shows a cross sectional view of the portion 53 of the catheterferrule 52 enclosing the ‘O’-ring housing 50. The square inner profile53 of catheter ferrule 52 prevents the ‘O’-ring housing 50 from rotatinginside the catheter ferrule 52. This is done to provide resistance torotational forces on the ‘O’-ring housing as the grooved portion of thecatheter fiber connector 32 rotates inside the ‘O’-ring 46. Clearance isprovided between the ‘O’-ring housing 50 and the inner wall of thecatheter ferrule 52 to allow the ‘O’-ring housing 50 to float inside thecatheter ferrule 52.

[0039] A flexible drive shaft 58 is provided for rotating the catheterfiber 60 inside a human body. The drive shaft 58 encloses the catheterfiber along the length of the catheter outside of the fiber connector.The drive shaft 58, preferably, possesses both a high torsionalstiffness and a low bending stiffness. This allows the drive shaft 58 torotationally drive the catheter fiber 60 while allowing the drive shaft58 to bend along the path of a body lumen. The drive shaft 58 may, forexample, be made of two counterwound layers of multifilar coils, whichare commonly used in Intravascular Ultrasound (IVUS) catheters. Theproximal end of the driveshaft 58 is sealed onto the catheter connector32, e.g., with epoxy 48, to create a liquid tight seal to prevent fluidfrom contaminating the catheter fiber connector 32. A conical strainrelief 54 is provided at the tip of the OCT catheter connector 1 toprevent damage to the catheter fiber 60 or the drive shaft 58 by evenlydistributing bending forces as the catheter is pulled to the side. TheOCT connector further includes a catheter shaft 56 running though theaxis of the ‘O’ ring housing 50 and the conical strain relief 54. Thecatheter shaft 56 is attached to the ‘O’-ring housing, e.g., with epoxy.Of course, any structures in any embodiment which are attached by epoxyor adhesive can instead be attached by any other means. The drive shaft58 runs through the catheter shaft 56 and rotates inside the cathetershaft 6.

[0040]FIG. 5 shows a front-end view of the OCT catheter connector 1 andthe motor unit 3. This view shows that the shape of the catheter ferrule52 is preferably asymmetrical so that there is only a one-way fit of thecatheter connector 1 into the motor nose 14. This is desirable becausethe ends of the optical fibers 4 and 60 are preferably angled tominimize back reflection of the optical signal. Because the ends ofoptical fibers 4 and 60 are angled, they have to be coupled together ata particular orientation. The one-way fit of the catheter connector 1into the motor nose is used to ensure that the catheter fiber 60 isproperly orientated with the motor fiber 4. This prevents an operatorfrom trying to force the catheter fiber connector 32 into thefiber-to-fiber adapter 10 in an improper orientation, which could causedamage to one or both ends of the optical fibers 4 and 60.

[0041]FIG. 6 shows a radial cross-sectional view of the OCT connector 1taken through the grippers 34 and looking distally. The catheter ferrulewall 74 has two slots 72 through which the grippers 34 contact theadapter 30 to push the catheter connector fiber 32 into properengagement with the fiber-to-fiber adapter 10.

[0042]FIG. 7 shows an axial cross-sectional view of the OCT connectionsystem, in which the entire motor unit 3 is shown. Light from a lightsource (not shown), e.g., a laser, enters the OCT connection systemthrough an optical fiber 80, which is part of a connector/fiber/lensassembly 82. The light in the fiber 80 is collimated by a GRIN lens 84.The lens housing 86 is mounted to a five-axis positioner 88 with epoxy89. The five-axis positioner 88 is mounted to positioner mount 90 withscrews and is rotationally stationary. The five-axis positioner 88allows adjustment of the collimated beam 92 from the lens 84 such thatits optical axis is collinear with the rotational axis of the shaftrotary shaft 94. The collimated beam 92 enters a GRIN lens 96 of thelens/fiber/connector assembly 98, which can rotate within the motor unit3. The lens/fiber/connector assembly 98 is adjusted with an activefeedback system such that its optical axis is collinear and concentricwith the rotational axis of the rotary shaft 94. The GRIN lens 96focuses the collimated beam 92 into the motor fiber 4, which transmitsan optical signal from the catheter optical fiber 60 when the two fibers4 and 60 are coupled together. The motor unit 3 also transmits thereflected beam received from the catheter optical fiber 60 along thesame optical path to the optical fiber 80. The optical fiber 80 thentransmits the reflect beam to an interferometer (not shown) to beprocessed.

[0043] The rotary shaft 2 rotates with two precision bearings 102 and isrotated by a motor 104, which provides drive torque to rotate the shaft2 and the fiber-to-fiber adapter 10. When the motor unit 3 and the OCTcatheter connector assembly 1 are mated, the fiber-to-fiber adapter 10transfers this drive torque to rotate the catheter fiber connector 32,the catheter fiber 60 and the flexible drive shaft 56 of the catheterconnector 1.

[0044]FIG. 8 shows an axial cross-section of an OCT catheter proximalconnector 120 according to a second example embodiment. The OCT catheterconnector 120 includes a catheter ferrule 124 and a retainer 125 withinthe catheter ferrule 124. The catheter ferrule 124 is constructed of asoft flexible polymer, such as PEBAX 2533. The retainer 125 isconstructed of a rigid polymer such as polycarbonate or PEEK to providerigidity to the catheter ferrule 124. The OCT catheter connector 120further includes a connector bushing 128 rotatably housed in theretainer 125 and a catheter fiber connector 122 attached to theconnector bushing 128 by an epoxy 130. The connector bushing 128 hasribs 127 positioned at elliptical cutouts 129 in the retainer 125. Thecatheter optical fiber 123 runs along the rotational axis of thecatheter fiber connector 122.

[0045] The OCT catheter connector 120 according to this embodiment ismated to a motor unit (not shown) by slightly squeezing a grip area 126of the catheter ferrule 124 corresponding to the elliptical cutouts 129of the retainer 125. This deforms the cylindrical cross-section of thecatheter ferrule 124 within the grip area 126, causing the ferrule 124to contact ribs 127 of the connector bushing 128 through the cutout 129of the retainer 125. This mechanism provides a means for grasping and/ortransferring force to the catheter fiber connector 122 to push it intoproper engagement with the motor unit (not shown). When the OCT catheterconnector 120 is mated to the motor unit, the catheter ferrule 124elastically regains its original shape, allowing the connector bushing128 and the catheter fiber connector 122 to freely rotate with nofriction or side loading forces that negatively affects the sensitivefiber connection. The retainer 125 extends the entire length of thecylinder portion of the ferrule 124, providing rigidity to transferloads from the catheter without interfering with the free rotation ofthe catheter fiber connector 122 and the connector bushing 128. As inthe previous embodiment, a seal 132, preferably an ‘O’-ring, is providedto prevent fluids from contaminating the catheter fiber connector 122and the motor unit. Preferably, the ‘O’-ring housing 134 issubstantially cylindrical, except for a square portion 137 housed in asquare portion 138 of the catheter ferrule 124 to resist rotationalforces caused by friction between the catheter fiber connector 122 andthe ‘O’-ring 132 during rotation. The catheter ferrule 124 can also beused to prevent rotation of the catheter caused by friction imparted tothe seal 132 by bonding the catheter shaft 138 inside the strain relief136 or the catheter ferule 124 with epoxy 140. The catheter ferrule 124is held rotationally stationary through frictional contact with themotor nose, which is not shown in this detail, but is substantiallyequivalent to those described in the previous embodiments.

[0046] The OCT connector 120 according to this embodiment also includesa shield 135 running around the outer cylindrical surface of thecatheter ferrule 124 to help maintain a sterile field by forming asterile barrier between the clinician's sterile hand, which holds theOCT catheter connector 120 during the connection procedure, and thenon-sterile motor unit (not shown). Other imaging catheter connectionprocedures require the non-sterile motor unit to be bagged in apolyethylene bag to reduce the risk of sterile field contamination.While the polyethylene bag provides a sterile barrier between theclinician's hand and the motor unit, it sometimes prevents properengagement between the catheter connector and the motor unit because itmust extend over the distal end of the motor unit to serve as aneffective shield. The shield 135 also serves as a means to prevent theclinician's hand from slipping as he or she pushes the OCT connectorinto engagement with the motor unit. The catheter ferrule has short ribs133 on its outer cylindrical surface, which mates with a cylindricaldepression on the motor unit. The short ribs 133 snap into matinggrooves in the cylindrical depression of the motor unit. This engagementprovides a positive locking mechanism to prevent unwanted disconnectionof the OCT catheter connector 120 in case of strong tensile forceapplied to the catheter shaft 138.

[0047]FIG. 9 shows an axial cross-section of a third example embodimentof the OCT catheter connector 150. This embodiment preferably performsall the functions described in the previous embodiments, but utilizescomponents that are less expensive to fabricate and reduces thecomponent count as well. Some of the desirable features of a goodconnection system include a quick and easy attachment procedure usingone sterile hand, clearly identifiable alignment indicators and apositive indication of proper engagement, e.g., an audible click. Thisembodiment avoids the use of a plastic bag that serves as a sterilebarrier for the motor unit in IVUS products and the embodiment shown inFIG. 1 interfering with the finger tabs function.

[0048] The motor unit according to this example embodiment includesthree spring-loaded ball plungers 170 radially located 120 degrees aparton the opening 157 of the motor nose 156. Each of the three ballplungers 170 has a spring loaded spherical ball adapted to engage acorresponding concave depression 162 in the catheter ferrule 166. Thisengagement secures the OCT connector 150 to the motor unit viafrictional resistance, which resists torsional forces from the seal 168,such as an ‘O’-ring, and pulling forces from the catheter. The motornose 156 includes a bendable wave or Belleville washer 154 secured tothe inside the motor nose 156 and surrounding the fiber-to fiber adapter152.

[0049] To insert the OCT connector 150 into the motor unit, a cliniciangrips the catheter ferrule 166 and pushes it into the motor unit. As thecatheter ferrule 166 is pushed into the motor unit, the distal end ofthe connector bushing 177 contacts a portion 178 of the inner wall ofthe catheter ferrule 166. This contact causes the portion 178 of theinner wall to push against the connector bushing 177, which in turncauses the connector bushing 177 to push the catheter fiber connector160 into engagement with the fiber-to-fiber adapter 152. Also duringinsertion of the OCT connector 150 into the motor unit, the proximal endof the catheter ferrule 166 pushes the washer 154 inwardly. When theclinician releases the catheter ferrule 166, the washer 154 pushes thecatheter ferrule 166 distally with respect to the connector bushing 177.This causes the portion 178 of the inner wall of the catheter ferrule tomove away from the connector bushing 177, allowing the connector bushing177 and the fiber connector 160 to freely rotate within the catheterferrule 166 without friction or side loading that could compromiseperformance during operation.

[0050] The catheter ferrule 166 is preferably constructed of a rigid,injection moldable material as a one or two piece assembly comprisingthe cylindrical portion of the ferrule 166 and the shield 164 attachedwith adhesive. The plastic bag used with IVUS products to serve as ashield can still be used because the non-sterile motor unit is laid inthe sterile field, but the bag will not be used as a sterile barrier toprotect the clinician's hand from the non-sterile motor unit. Instead,the shield 164 acts as a sterile barrier to prevent the contamination ofthe clinician's sterile hand during attachment of the catheter to thenon-sterile motor unit.

[0051] Referring to FIGS. 9 and 10, the seal arrangement of thisembodiment differs from the previous embodiments. The seal 168, which ispreferably an ‘O’-ring, seals around a gland 174 instead of a groovedportion of the catheter connector. The gland 174 is a stainless steeltube with a smooth outer surface finish that is bonded into the fiberconnector 162 using epoxy to form a high-pressure seal. As in theprevious embodiments, an ‘O’-ring housing is fitted around the ‘O’-ring.Four drain holes 172 are provided on the catheter ferrule to allow fluidleakage to drain through the wall of the ferrule 166 to reduce thelikelihood of contamination of the motor unit and the fiber opticconnector 162 if the seal should leak during high-pressure infusion.

[0052] The catheter connector includes a tab 182 adapted to be receivedin a slot 183 in the fiber-to-fiber adapter 152. The tab 182 and theslot 183 in the fiber-to-fiber adapter 152 provide for a one-way fit ofthe catheter connector 150 into the motor unit. This is desirable toprevent an operator from trying to force the catheter fiber connector160 into the fiber-to-fiber adapter 152 in an improper orientation,which could cause damage to one or both halves of the optical connectormating pair.

[0053] While various embodiments of the application have been described,it will be apparent to those of ordinary skill in the art that many moreembodiments and implementations are possible that are within the scopeof the subject invention. For example, each feature of one embodimentcan be mixed and matched with other features shown in other embodiments.Features known to those of ordinary skill in the art of optics maysimilarly be incorporated as desired. Additionally and obviously,features may be added or subtracted as desired. Therefore, the inventionis not to be restricted or limited except in accordance with thefollowing claims and their equivalents.

1. An optical catheter connector comprising: a hollow catheter ferrulehaving an opening; a fiber connector rotatably housed inside thecatheter ferrule; an optical fiber positioned along a rotational axis ofthe fiber connector; and a fiber ferrule attached to the fiberconnector, wherein the fiber ferrule supports one end of the opticalfiber.
 2. The catheter connector of claim 1, wherein the fiber ferruleextends outwardly from the opening of the catheter ferrule.
 3. Thecatheter connector of claim 1, further comprising a connector bushinghoused inside the catheter ferrule and attached to the fiber connector.4. The catheter connector of claim 3, wherein the connector bushing hasat least two slots, the catheter ferrule has a slot openingcorresponding to each slot on the connector bushing, and the catheterconnector further comprises: at least two lock tabs attached to theouter surface of the catheter ferrule; and a gripper attached to eachlock tab and adapted to engage one of the slots on the connector bushingthrough the corresponding slot opening in the catheter ferrule.
 5. Thecatheter connector of claim 4, wherein the lock tabs are made ofpolycarbonate.
 6. The catheter connector of claim 4, wherein the locktabs are made of plastic.
 7. The catheter connector of claim 1, furthercomprising a drive shaft attached at one end to the fiber connector,wherein the drive shaft encloses a length of the optical fiber.
 8. Thecatheter connector of claim 7, wherein the driver shaft has a hightorsional stiffness and a low bending stiffness.
 9. The catheterconnector of claim 1, further comprising a seal sealed around a portionof the fiber connector.
 10. The catheter connector of claim 9, whereinthe seal is an ‘O’ ring.
 11. The catheter connector of claim 10, furthercomprising an ‘O’ ring housing fitted around the ‘O’ ring, wherein the‘O’ ring housing is housed inside the catheter ferrule.
 12. The catheterconnector of claim 11, wherein the portion of the catheter ferruleenclosing the ‘O’ ring housing has an inner wall that is shaped toprevent the ‘O’ ring housing from rotating inside the catheter ferrule.13-33. (Cancelled)